The invention relates to the technical sector of apparatus for batching powder and/or granular products internally of container elements, such as vials or envelopes, for example moving on an advancement line, as well as a method for batching the powder and/or granular products internally of container elements.
U.S. Pat. No. 4,640,322 describes an apparatus for filling container elements with powder products, which can operate in controlled atmospheric conditions; this apparatus comprises: a hopper for containing the powder products; a batching chamber comprising an inlet connected to the hopper, an outlet aligned time by time with respective transiting container elements, and an internal passage having a vertical development; an element which is permeable to gas which superiorly delimits the passage; a discharge valve acting functionally in the passage, below the product inlet, and mobile between an open position and a closed position, in which it respectively enables and prevents communication between the passage and the outlet, with the valve identifying, in the closed position thereof and together with the permeable element, an internal cavity; means for depressing for aspirating a given quantity of product from the hopper through the inlet and internally of the cavity when the valve is in the closed position; pressurized means destined to project the quantity of products, thus loaded internally of the cavity, through the passage outlet and internally of a corresponding container element when the valve is in the open position.
In the region the valve operates in, the portions of the walls delimiting the internal passage are constituted by a deformable elastic membrane; the valve comprises an obturator element destined to act from the outside in a transversal direction to the passage, intercepting and pressing the elastic membrane towards the passage wall facing it; the obturator element thus acts between the closed position, in which the elastic membrane encounters the facing wall of the passage, with a consequent total obstruction of the passage, and the open position in which the internal cavity, due to the elastic reaction of the membrane, is in communication with the outlet of the passage in order to enable transit of the powder products.
Some drawbacks of this solution consist in the rapid deterioration of the elastic membrane and its possible perforation, imputable to the continuous deformation stress the membrane is subjected to during apparatus functioning; this requires frequent substitutions of the membrane, all of which limits the apparatus productivity and in any cases reduces its reliability.
The above-described apparatus enables adjustment of the relative position of the permeable element internally of the passage, such that it is possible to define the quantity of powder products which must be loaded in the cavity and thus the batch thereof destined to be introduced into a corresponding container element; during the loading stage, however, an unknown quantity of product, variable for each operative cycle, falls into the volume identified between the inlet and the underlying deformed elastic membrane (obturator element in the closed position). In consequence of this, the quantity of product projected into the underlying container elements can deviate quite noticeably from the requested amount; this represents a particularly disqualifying drawback in applications where the tolerances are very low, for example when the products are particularly expensive (for example: cosmetic products) or are for medical use.
A further drawback of the above-described apparatus is that it is impossible to reproduce identical operating cycles, in particular to constantly generate a same jet of compressed gas for projecting a batched quantity, priorly loaded into the int4rnal cavity, internally of a corresponding container element; indeed, the projection of each jet of compressed gas is done by timed activation of a solenoid valve, functionally connected to the pressurized source, which exhibits, as an intrinsic characteristic, variable response times.